As described in copending U.S. patent application Ser. No. 13/420,142, which is incorporated herein by reference in its entirety, Masonry veneer systems are commonly used for exterior cladding, as architectural or aesthetic features on residential and commercial buildings.
As described in detail by the Masonry Veneer Manufacturers Association (MVMA), proper installation of stone on a framed building requires the installation of a weather resistant barrier (WRB), then application of a lath secured to the framing with corrosion resistant fasteners and a nominal ½ inch scratch coat. The lath must be properly applied to the wall in order to avoid intrusion of water, and to provide an acceptable structure to which the cladding will be adhered. The lath must be corrosion resistant, applied in an overlapping fashion, and with a corrosion resistant nail that penetrates the studding according to the MVMA recommendations. Additionally, the scratch coat must be applied using a correct mortar at the proper moisture content and thickness, embedded properly in the lath, allowed to cure to “thumb dry”, the scratched to provide grooves, and allowed to cure. These additional products and steps add cost, additional labor and provide opportunities for human error, which can result in a poor installation and future problems. The installation of the WRB, lath and scratch coat must be performed up to 48 hours or more before the installation of the veneer product, allowing the scratch coat to properly cure. Further details are set forth by the MVMA.
Once the scratch coat is properly applied and cured, adhered concrete masonry veneer (ACMV) products are then adhered to the scratch coat using a mortar applied to the ACMV. The MVMA guidelines recommend that the scratch coat should be moist cured to prevent cracking, and that both the scratch coat and the ACMV should be “dampened” when applying the ACMV, adding additional requirements on the installer. The installer typically will take individual ACMV products, “butter” the back of each individual product with mortar, and apply the “buttered” product to the scratch coat, forcing the mortar into the scratch coat to adhere the ACMV to the wall. The consistency of the scratch coat, mortar and skill of the installer each play a role in the reliability of the installation. Additionally, the installation should not be performed during rain or cold weather, thus limiting the time available (and time delay) for completion of the building. These all add to cost and customer dissatisfaction during the construction process.
ACMV products are typically installed as discrete individual stones or brick adhered to a scratch coat on the exterior of a building as described above. Stones are typically installed from the top of the building, and the wall is covered in a downward direction. If the wall is struck (e.g. if drywall is installed on the interior of the building) before the mortar is cured, the stone may be dislodged from the wall. This creates re-work for the installer, or partially dislodged stones may become loose at a later date.
An optional installation technique described in the MVMA guidelines includes a rainscreen drainage plane system, which provides a space to permit incidental water to escape. The recommended ways to provide this space include a drainage mat, formed polymer sheeting (such as Delta®-Dry Stucco and Stone, available from Cosella-Dorken, ref. http://www.cosella-dorken.com), strapping or furring to provide the recommended MVMA air gap of 3/16 to ¾ inch. These systems allow moisture to escape from behind the veneer, but add additional material and labor cost, time and complexity during installation of the ACMV product, and are not used in many installations.
A panelized veneer product, Versetta Stone, is sold by Boral Stone, LLC. (http://masonry.owenscoming.com/versettastone). These panelized veneer products are secured to the exterior of a building using mechanical fasteners driven through a flange embedded in the top of the veneer product. These systems reduce some of the issues with the adhered ACMV products, because the lath, scratch coat and adhesive mortar can be eliminated in many installations of these panelized veneer products. However, these panelized veneer products are relatively large (typically about 8-10 inches high and approximately 32-36 inches wide) and have a limited drainage plane gap. While this enables fast installation on structures where penetrations are not present (such as windows or outlets) or corners, the presence of these penetrations on most buildings results in a large number of panels being trimmed and a fairly large amount of waste (Boral's installation instructions instructs an installer to initially estimate 10% scrap). The large number of cuts takes time and produces excess waste. Additionally, these products are more expensive to manufacture, and the designs present challenges in manufacturing.
Accordingly, it would be desirable to provide an improved product and system for installing veneer products and to eliminate the lath and scratch coat.